Deciphering Bulk Lithium Dendrite Evolution in Solid-State Electrolytes Driven by Electron Leakage and Biaxial Pressures.

Solid-state lithium metal batteries (SSLMBSs) are promising candidates for next-generation energy storage. However, practical application is severely hindered by bulk lithium dendrite nucleation and growth induced by electron leakage at the grain boundaries (GBs) of solid electrolytes, alongside interfacial dendrite growth. Existing studies predominantly treat electron leakage and mechanical stress in isolation, failing to systematically elucidate their coupled regulatory mechanisms on bulk dendrite evolution. To bridge this gap, we develop an electro-chemo-mechanical phase-field model of lithium dendrite nucleation and growth. This framework dynamically captures the complete evolution of dendrite nucleation and growth. By introducing key quantitative metrics, including average nucleation probability, nucleation distribution uniformity, bulk dendrite fraction, and penetrating risk, we reveal how electron concentration, stacking pressure, and lateral pressure govern bulk dendrite evolution. Furthermore, through multiparameter contour maps, we unambiguously established the absolute dominance of electron concentration in driving dendrite nucleation and global growth. Crucially, we elucidate the strict directional selectivity and competing trade-offs between stacking and lateral pressures in modulating dendrite evolution and mitigating penetration risk. This study provides a robust theoretical foundation for the synergistic optimization of GB electronic properties and operational biaxial pressures, offering rational strategies to fundamentally enhance the safety of SSLMBs.